INTRASPECIFIC COMPETITION IN ANOPHELES STEPHENSI (DIPTERA: CULICIDAE): II. THE EFFECTS OF MORE CROWDED DENSITIES AND THE ADDITION OF ANTIBIOTICS

1977 ◽  
Vol 109 (11) ◽  
pp. 1475-1480 ◽  
Author(s):  
William K. Reisen ◽  
Richard W. Emory
Keyword(s):  
Emerging Adults ◽  
Amphotericin B ◽  
Intraspecific Competition ◽  
Anopheles Stephensi ◽  
Larval Mortality ◽  
Indirect Evidence ◽  
Penicillin G ◽  
Microbial Populations ◽  
Inhibitory Compounds ◽  
Developmental Rates

AbstractAnopheles stephensi Liston larvae were reared in food- and space-limited environments to which a mixture of penicillin G, chloramphenicol, and amphotericin B was added to suppress microbial populations. Under crowded conditions larvae took longer to develop, exhibited reduced survival, had an extended pupation period, and produced adults that were smaller. Under uncrowded conditions slightly more males than females emerged, whereas under crowded conditions proportionately fewer males than females emerged. Indirect evidence suggested that inhibitory compounds that slowed development and increased larval mortality were produced by crowded larvae. The addition of antibiotics did not suppress all microbial populations, but rather selected for resistant Pseudomonas-group bacteria which actually increased in number. The addition of antibiotics increased developmental rates at uncrowded, but not crowded densities, increased larval mortality, and increased the size of the emerging adults. Residual antibiotics increased development rates in a subsequent bioassay of the rearing media.

Laboratory and field trials to determine the modes of action of malathion and diesel oil against Culicoides furens (Poey) (Dipt., Ceratopogonidae)

1971 ◽  
Vol 60 (3) ◽  
pp. 399-407
Author(s):  
John B. Davies
Keyword(s):  
Emerging Adults ◽  
Larval Mortality ◽  
Adult Emergence ◽  
Field Trials ◽  
Diesel Oil ◽  
Modes Of Action ◽  
Marine Diesel ◽  
Pupal Mortality

One field and four laboratory trials were run to determine the reason for the success of 1–8% malathion in diesel oil in controlling Culicoides furens (Poey) in swamp mud in Jamaica. In the laboratory malathion and marine diesel oil (1:4000) was an effective larvicide for up to two days after application to the mud, but diesel oil alone gave only slight mortality even after six days. Judged by the emergence of adults, diesel oil gave 100% pupal mortality for five days and still showed some effect after four weeks; this effect was not improved by the addition of malathion. In the field, counts of emerging adults showed that diesel oil at 106–5 gal/acre gave 97–8% control of C. furens for up to eight weeks after application. It is concluded that, because of the possibility of pupicidal action, insecticides should be assessed on adult emergence rather than larval mortality.

The effect of some cowpea varieties on the development and survival of larvae of the seed moth, Cydia ptychora (Meyrick) (Lepidoptera: Tortricidae)

1978 ◽  
Vol 68 (1) ◽  
pp. 57-64 ◽  
Author(s):  
R. M. Perrin
Keyword(s):  
Emerging Adults ◽  
Larval Mortality ◽  
Small Degree ◽  
First Instar ◽  
Fresh Food ◽  
Cydia Ptychora ◽  
Cowpea Varieties ◽  
Natural Situation ◽  
Mature Seeds

AbstractIn studies in Nigeria, survival and weight increase of the larvae of Cydia ptychora (Meyr.) were affected by the variety of cowpea (Vigna unguiculata) on which they fed. The weights of fifth-instar larvae immediately prior to pupation and the amount of fresh food ingested were similar on three varieties when loose seeds were fed, but in a more natural situation, larvae appeared to face a manoeuvrability problem in small pods, which resulted in reduced weight gain. Differences in weight due to diet were less pronounced in emerging adults. Larval mortality was greatest on two varieties with large pods and may have been related to the nutritional quality of mature seeds or the presence of toxic chemicals. Some first-instar larvae died during the pod-boring process, particularly in the variety Vita-5. Two known susceptible varieties produced a moderate-to-small degree of mortality and large females. Significantly greater weight was attained when larvae fed for five days on 10-day-old seed followed by 15-day-old seed, or on 15-day-old seed throughout, than on 15-day-old seed followed by dried seed, or on 10-day-old seed throughout. Ovipositing females seemingly select pods of an age that minimises exposure of young larvae to drying or fully dried seed, which is a relatively unsuitable diet.

Larval intraspecific competition for food in the European grapevine moth Lobesia botrana

2014 ◽  
Vol 104 (4) ◽  
pp. 517-524 ◽  
Author(s):  
D. Thiéry ◽  
K. Monceau ◽  
J. Moreau
Keyword(s):  
Life History ◽  
Intraspecific Competition ◽  
Life History Traits ◽  
Larval Mortality ◽  
Lobesia Botrana ◽  
Reproductive Capacity ◽  
Strong Increase ◽  
European Grapevine Moth ◽  
Grapevine Moth ◽  
Larval Crowding

AbstractEffective pest management with lower amounts of pesticides relies on accurate prediction of insect pest growth rates. Knowledge of the factors governing this trait and the resulting fitness of individuals is thus necessary to refine predictions and make suitable decisions in crop protection. The European grapevine moth, Lobesia botrana, the major pest of grapes in Europe, is responsible for huge economic losses. Larvae very rarely leave the grape bunch on which they were oviposited and thus cannot avoid intraspecific competition. In this study, we determined the impact of intraspecific competition during the larval stage on development and adult fitness in this species. This was tested by rearing different numbers of larvae on an artificial diet and measuring developmental and reproductive life history traits. We found that intraspecific competition during larval development has a slight impact on the fitness of L. botrana. The principal finding of this work is that larval density has little effect on the life history traits of survivors. Thus, the timing of eclosion, duration of subsequent oviposition, fecundity appears to be more uniform in L. botrana than in other species. The main effect of larval crowding was a strong increase of larval mortality at high densities whereas the probability of emergence, sex ratio, pupal mass, fecundity and longevity of mated females were not affected by larval crowding. Owing to increased larval mortality at high larval densities, we hypothesized that mortality of larvae at high densities provided better access to food for the survivors with the result that more food was available per capita and there were no effect on fitness of survivors. From our results, larval crowding alters the reproductive capacity of this pest less than expected but this single factor should now be tested in interaction with limited resources in the wild.

scholarly journals Putative Role of β-1,3 Glucans in Candida albicans Biofilm Resistance

2006 ◽  
Vol 51 (2) ◽  
pp. 510-520 ◽  
Author(s):  
Jeniel Nett ◽  
Leslie Lincoln ◽  
Karen Marchillo ◽  
Randall Massey ◽  
Kathleen Holoyda ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Cell Viability ◽  
Amphotericin B ◽  
Cell Walls ◽  
Positive Impact ◽  
Indirect Evidence ◽  
Phenotypic Properties

ABSTRACT Biofilms are microbial communities, embedded in a polymeric matrix, growing attached to a surface. Nearly all device-associated infections involve growth in the biofilm life style. Biofilm communities have characteristic architecture and distinct phenotypic properties. The most clinically important phenotype involves extraordinary resistance to antimicrobial therapy, making biofilm infections very difficulty to cure without device removal. The current studies examine drug resistance in Candida albicans biofilms. Similar to previous reports, we observed marked fluconazole and amphotericin B resistance in a C. albicans biofilm both in vitro and in vivo. We identified biofilm-associated cell wall architectural changes and increased β-1,3 glucan content in C. albicans cell walls from a biofilm compared to planktonic organisms. Elevated β-1,3 glucan levels were also found in the surrounding biofilm milieu and as part of the matrix both from in vitro and in vivo biofilm models. We thus investigated the possible contribution of β-glucans to antimicrobial resistance in Candida albicans biofilms. Initial studies examined the ability of cell wall and cell supernatant from biofilm and planktonic C. albicans to bind fluconazole. The cell walls from both environmental conditions bound fluconazole; however, four- to fivefold more compound was bound to the biofilm cell walls. Culture supernatant from the biofilm, but not planktonic cells, bound a measurable amount of this antifungal agent. We next investigated the effect of enzymatic modification of β-1,3 glucans on biofilm cell viability and the susceptibility of biofilm cells to fluconazole and amphotericin B. We observed a dose-dependent killing of in vitro biofilm cells in the presence of three different β-glucanase preparations. These same concentrations had no impact on planktonic cell viability. β-1,3 Glucanase markedly enhanced the activity of both fluconazole and amphotericin B. These observations were corroborated with an in vivo biofilm model. Exogenous biofilm matrix and commercial β-1,3 glucan reduced the activity of fluconazole against planktonic C. albicans in vitro. In sum, the current investigation identified glucan changes associated with C. albicans biofilm cells, demonstrated preferential binding of these biofilm cell components to antifungals, and showed a positive impact of the modification of biofilm β-1,3 glucans on drug susceptibility. These results provide indirect evidence suggesting a role for glucans in biofilm resistance and present a strong rationale for further molecular dissection of this resistance mechanism to identify new drug targets to treat biofilm infections.

ANALYSIS OF MORTALITY IN THE APPLE MAGGOT, RHAGOLETIS POMONELLA (DIPTERA: TEPHRITIDAE), IN QUEBEC

1977 ◽  
Vol 109 (6) ◽  
pp. 769-788 ◽  
Author(s):  
P. J. Cameron ◽  
F. O. Morrison
Keyword(s):  
Emerging Adults ◽  
Larval Mortality ◽  
Experimental Studies ◽  
Pupal Stage ◽  
Life Tables ◽  
Population Variation ◽  
Key Factors ◽  
Early Variety ◽  
Successive Generations ◽  
Pupal Mortality

AbstractLife tables were constructed for populations of R. pomonella (Walsh) in two abandoned, heavily infested apple orchards near Como, Quebec. All life stages were sampled and the results expressed in terms of the apple as a unit. Twenty-five life tables, each based on one tree, covered two successive generations on both early and late maturing varieties.Natality was of no value in predicting variation in numbers of emerging adults, whereas the early pupal stage estimates explained over 80% of the variation. Parasitism of larvae and pupae was more common than previously recorded but parasites were not significant in the population dynamics of their host. Nutritionally based larval mortality, predation on mature larvae and pupae, and movements of adults between trees were key factors in population variation. Early variety trees appeared to maintain apple maggot population levels. These results were supported by experimental studies on the effects of temperature treatments and predation on larval and pupal mortality.

THE EFFECTS OF LARVAL INTRASPECIFIC COMPETITION ON IMAGINAL DENSITIES IN ANOPHELES STEPHENSI (DIPTERA: CULICIDAE): A LABORATORY EVALUATION

1977 ◽  
Vol 109 (11) ◽  
pp. 1481-1484 ◽  
Author(s):  
William K. Reisen ◽  
Richard W. Emory
Keyword(s):  
Sex Ratio ◽  
Continuous Culture ◽  
Intraspecific Competition ◽  
Anopheles Stephensi ◽  
Laboratory Evaluation ◽  
Adult Density

AbstractExperiments with caged populations of Anopheles stephensi Liston were performed to evaluate the effects of larval intraspecific competition on adult density and sex ratio. The changing of the water in continuous culture cages prevented the accumulation of larval competitive compounds and excretory products, and resulted in higher adult densities and the successful emergence of proportionately more males.

scholarly journals Factors affecting fungus-induced larval mortality in Anopheles gambiae and Anopheles stephensi

2010 ◽  
Vol 9 (1) ◽  
pp. 22 ◽  
Author(s):  
Tullu Bukhari ◽  
Anthonieke Middelman ◽  
Constantianus JM Koenraadt ◽  
Willem Takken ◽  
Bart GJ Knols
Keyword(s):  
Anopheles Gambiae ◽  
Anopheles Stephensi ◽  
Larval Mortality ◽  
Factors Affecting

scholarly journals Direct Observation of the Dynamics of Single-Cell Metabolic Activity during Microbial Diauxic Growth

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
H. L. O. McClelland ◽  
C. Jones ◽  
L. M. Chubiz ◽  
D. A. Fike ◽  
A. S. Bradley
Keyword(s):  
Single Cell ◽  
Metabolic Activity ◽  
Single Cells ◽  
Indirect Evidence ◽  
Biomedical Science ◽  
Microbial Populations ◽  
Diurnal Changes ◽  
Diauxic Growth ◽  
Content Type ◽  
Regulatory Cascade

ABSTRACT Population-level analyses are rapidly becoming inadequate to answer many of biomedical science and microbial ecology’s most pressing questions. The role of microbial populations within ecosystems and the evolutionary selective pressure on individuals depend fundamentally on the metabolic activity of single cells. Yet, many existing single-cell technologies provide only indirect evidence of metabolic specialization because they rely on correlations between transcription and phenotype established at the level of the population to infer activity. In this study, we take a top-down approach using isotope labels and secondary ion mass spectrometry to track the uptake of carbon and nitrogen atoms from different sources into biomass and directly observe dynamic changes in anabolic specialization at the level of single cells. We investigate the classic microbiological phenomenon of diauxic growth at the single-cell level in the model methylotroph Methylobacterium extorquens. In nature, this organism inhabits the phyllosphere, where it experiences diurnal changes in the available carbon substrates, necessitating an overhaul of central carbon metabolism. We show that the population exhibits a unimodal response to the changing availability of viable substrates, a conclusion that supports the canonical model but has thus far been supported by only indirect evidence. We anticipate that the ability to monitor the dynamics of anabolism in individual cells directly will have important applications across the fields of ecology, medicine, and biogeochemistry, especially where regulation downstream of transcription has the potential to manifest as heterogeneity that would be undetectable with other existing single-cell approaches. IMPORTANCE Understanding how genetic information is realized as the behavior of individual cells is a long-term goal of biology but represents a significant technological challenge. In clonal microbial populations, variation in gene regulation is often interpreted as metabolic heterogeneity. This follows the central dogma of biology, in which information flows from DNA to RNA to protein and ultimately manifests as activity. At present, DNA and RNA can be characterized in single cells, but the abundance and activity of proteins cannot. Inferences about metabolic activity usually therefore rely on the assumption that transcription reflects activity. By tracking the atoms from which they build their biomass, we make direct observations of growth rate and substrate specialization in individual cells throughout a period of growth in a changing environment. This approach allows the flow of information from DNA to be constrained from the distal end of the regulatory cascade and will become an essential tool in the rapidly advancing field of single-cell metabolism.

scholarly journals PERFORMANCE OF Metarhizium rileyi APPLIED ON Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae)

2020 ◽  
Vol 7 (1) ◽  
pp. 60-65
Author(s):  
Elisângela De Souza Loureiro ◽  
Ricardo Alexandre De Souza Tosta ◽  
Pamella Mingotti Dias ◽  
Luis Gustavo Amorim Pessoa ◽  
Francisco Mendes de Oliveira Neto ◽  
...  
Keyword(s):  
Emerging Adults ◽  
Helicoverpa Armigera ◽  
Sublethal Effects ◽  
Larval Mortality ◽  
Tween 80 ◽  
Larval Phase ◽  
Metarhizium Rileyi ◽  
Filial Generation ◽  
Helicoverpa Armígera ◽  
Different Strains

This study aimed to evaluate the efficiency of different strains of the entomopathogenic fungus Metarhizium rileyi in the control of Helicoverpa armigera caterpillars in laboratory conditions. Caterpillars between the 2nd and 3rd instar were used, ranging in size from 0.7 to 1.2 cm length. The experimental design used was completely randomized, composed of five treatments and five replications, each one consisting of 50 insects. The treatments T1 - Control (sterile distilled water), T2 - M. rileyi UFMS 02 strain, T3 - M. rileyi UFMS 03 strain, T4 - M. rileyi UFMS 06 strain, and T5 - M. rileyi UFMS 07 strain were evaluated. All treatments were applied (2 mL/insect) in suspensions of the order of 1.0 × 109 conidia mL-1, and Tween 80® was added in all treatments. Evaluations were performed daily to verify mortality and sublethal effects. For emerging adults, Filial Generation (FG), the biological cycle was evaluated. The data referring to larval mortality for the Parental Generation (PG) and GF and pupal for GF were submitted to analysis of variance, and the Scott-Knott test grouped the averages at 5% probability. The strains tested did not provide pathogenicity in the larval phase of H. armigera for PG and FG. However, there was a reduction in oviposition in all treatments regarding the control. There was an effect on the reproductive phase of GF caterpillars exposed to M. rileyi.

Sign in / Sign up

Export Citation Format

Share Document